Heat exchanging element



Oct. 12, 1943.

H. D. STEVRICK HEAT EXCHANGING ELEMENT Filed July 25, 1941 WITNESSE.

Mae/w. /LMM,

1.1 ATTORNEYS.

Patented Oct. 12, 1943 UNITED STATES PATENT GFFICE 2,331,437 HEATEXCHANGING ELEMENT Harrison D. Sterick, Pittsburgh, Pa..v ApplicationJuly 23, 1941 Serial No. 403,614

4 Claims;

I'his invention relates to heat exchanging elements, and moreparticularly to such elements of the n type.

It is among the objects of this invention to provide a iin type heatexchanging element which is easy and inexpensive to produce, simple incorrstruction, easy to mount in position, and highly eiilcient forconducting heat to or from an object the temperature of which it isdesired to affect.

In accordance with this invention a strip of metal -is provided with aplurality of closely spaced transverse slits that form a row of verynarrow ribbon-like ns. The slits extend only part way across this stripso vthat the uns are integrally connected to a body portion whichextends lengthwise of thestrip. This body portion most suitably isspaced from both side edges of the strip to permit a row of ns to beformed on both sides of it. The strip'is bent or curved transversely toform a channel or tube-like mem-V ber with the body portion adapted toengage the object whose temperature is to be alected. The tins conductheat either to or from the body portion depending upon whether theelement is being used to cool or to heat the object to which it isattached. If the element is to be curved in the plane of the bodyportion the latter is provided with a series of holes to permit suchcurvature. These holes also make it easier to braze the body portion tothe object it is attached to.

The invention is illustrated in the accompanying drawing in which Fig. 1is a plan View of my heat exchanging element in its at condition beforeit has been bent transversely; Fig. 2 is an enlarged `transverse sectionthrough the nished element; Fig. 3 is a side view, partly broken away,showing the element mounted on a pipe coiled around a supporting member;Fig. 4 is a view similar .to Fig. 2 of a modication of the invention;Fig. 5 is a transverse section through a pair of concentric conduitsshowing the heat exchanging element of Fig. 2 inside the innersubstantially parallel slits 2 that extend inwardly from the oppositeside edges of the strip. The inner ends of the slits of the two rowsarespaced apart far enough to leave a solid body portion 3 extendinglengthwise of lthe strip along its center. l The slits in the strip forma plurality 'ol' very narrow ribbon-like heat conducting ilns 4integrally connected to the central bodyportion at their inner ends. Ifthe strip is cut with shearsit will curve transversely of its own accordas it is cut. If cut in such a manner that it lies at, the strip maythen by a. separate operation be curved transyersely so that the outerends of the fins of the two rows tend to overlap, as shown in Fig. 2, toform a tube-like element. In /actual practice the curvature of the finsis not uniform and the overlapping is quite irregular, so that there aremany projecting surfaces.

This heat exchanging element can be used in many places where it isdesired to either heat or cool an object. For example,referring to Fig.3 in either a hot water heater or a ref rgerating device the pipe 6through which the hot water or refrigerating fluid iiows is threadedthrough the tube-like heat exchanging element and then may be wrappedhelically around a supporting member 'l and secured in place. Thisclamps the body portion 3 of the heat exchanging element between thepipe and supporting member. In ease the supporting member is omittedAthe .body portion of the element is brazed or otherwise fastened to thepipe 6. If we assume that heatfrom a gas burner or the like rises aroundand .between the ns 4 of the heat exchanging element outside ofsupporting member 3, the ns will labsorb the heat and rapidly conduct itto the body .portion of the element from which it will be conducted `bypipe 6 to the water flowing through it. On the other hand, in v-arefrigerating device 4fins `l will take up the surrounding lwarm airandconduct .it to the refrigerant flowing through the coil, whereby the airaround the \ns will be cooled. Or, if a hot uid is owing through pipe 6,the 'fins will radiate the heat to the;surround ing atmosphere andthereby cool the fluid.

In the modification .shown "in Fig. .4 the body portion 8 of the heatexchanging element is oii center-iso.thatonerowof fins 9 is narrowerthan the other row H1. Also, the element is bent transversely so jthat achannel-like element is formed in which :the ltwo :rows of ns aresubstantially parallel Vand `the wide row extends beyond the narrow row.yAirithat ows across the outer ends of the short 'ns will be interceptedby the projecting portions iof the long ns. This type of element :cany`besubstituted for the one shown inlFig. 3 if desired.

Fig. .5 'illustrates :a Away vin which two of my heat exchanginglelements can be used. The inner conduit l2 mayfibe the smoke stack of afurnace, while the outer conduit I3 may lead to a room that is to beheated. Extending helically around the inner surface of the innerconduit is one of my heat exchanging elements the body portion 3 ofwhich is held tightly against the conduit by means of a spring wire coilI4 inserted in the element. Wrapped helically around the outside of theinner conduit is another of my heat exchanging elements which is held inposition by a wire I5 engaging the inner surface ol its body portion 8.If desired, these heat exchanging elements may both be of the form shownin Fig. 2 or in Fig. 4. The hot waste gases flowing through innerconduit I2 are absorbed by the inner heat exchanging element andconducted through the inner conduit to theheat exchanging element thatsurrounds it. From this element the heat is radiated into the spacebetween the two conduits and the air heated thereby is Conducted to aroom for heating it. In this way the waste gases of al furnace areutilized for heating purposes. v

My heat exchanging element, by having very narrow fins on both sides ofits central body portion, has substantially the maximum practicablesurface area exposed to the atmosphere. This results in a very highdegree of heat transfer. Due to the transverse curvature of the elementit is readily mounted on a pipe or around a supporting object, becauseit can be telescoped o over a pipe or retaining wire. It is much quickerto slip the element over a pipe than to wrap it around the pipe as ithas been necessary to do heretofore with similar types of heatexchangers.

In Fig. 6 a slightly modified heat exchanging element is shown mountedin a different way on a pipe.coil I6. The body portion I'I of theelement engages the pipe between the convolutions rather than inside ofthe coil. To permit the body portion to be bent laterally so that it canfollow the coil it is provided with a plurality of longitudinal openingsI8 that allow the body portion to give laterally. These openings alsomake it easy to solder the body' portion to the pipe at spacedintervals, wherefore a separate supporting or attaching member isunnecessary. It will be observed that with this manner of mounting myheat exchanging element the ends of the ns I9 are disposed between thepipe convolutions instead of outside of the coil.

Many other uses for my heat exchanging elements will be apparent. Onesuch use is the cooling ofair cooled airplane motors.

According to the provisions of the patent statutes, l'. have explainedthe principle and construction of my invention and have illustrated anddescribed what I now consider to represent its best embodiment. However,I desire to have it understood that, Within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallyillustrated and described.

I claim:

1. The combination with a supporting member, of a heat exchangingelement in the form of a metal strip having a body portion extendinglengthwise thereof and spaced inwardly from the side edges of the strip,said strip being provided with a plurality of closely spaced slitsextending outwardly from both sides of said body portion to said edgesof the strip and forming two rows of narrow fins, said strip beingcurved transversely and coiled around said supporting member, and acoiled pipe engaging the inner surface of said body portion and holdingit against the supporting member.

2. In combination, a metal strip having a central body portion extendinglengthwise thereof and having a plurality of closely spaced slitsextending outwardly from both sides of said body portion to the sideedges of the strip whereby to form two rows of ribbon-like fins, saidstrip being curved transversely to form a tube-like element with saidtwo rows of fins partially overlapping, and a pipe extending throughsaid tube-like element in engagement therewith.

3. In a heat exchanging device, a coiled member, and a metal striphaving a central body portion extending lengthwise of itself and havinga plurality of closely spaced slits extending outwardly from both sidesof said body portion to the side edges of the strip whereby to form tworows of ribbon-like fins, said body portion extending lengthwise alongsaid coiled member in engagement therewith and with its surfacesubstantially parallel to the axis of the coil, and said fins extendingat least part way around said member.

4. In a heat exchanging device, a coiled pipe, and a metal strip havinga central body portion extending lengthwise of itself and having aplurality of closely spaced slits extending outwardly from both sides ofsaid body portion to the side edges of the strip whereby t0 form tworows of ribbon-like fins, said body portion extending lengthwise alon'gsaid coiled pipe in engagement therewith and with its surfacesubstantially parallel to the axis of the coil, and said ns extending atleast part way around said pipe.

HARRISON D. STERICK

